Posted
by
Unknown Lameron Monday March 03, 2014 @11:03PM
from the holding-out-for-an-atomic-cell-phone dept.

MTorrice writes "Lithium-sulfur batteries promise to store four to five times as much energy as today's best lithium-ion batteries. But their short lifetimes have stood in the way of their commercialization. Now researchers demonstrate that a sulfur-based polymer could be the solution for lightweight, inexpensive batteries that store large amounts of energy. Battery electrodes made from the material have one of the highest energy-storage capacities ever reported"
Litihium Ion batteries should maintain capacity for about 1000 cycles, whereas Lithium-sulfur batteries traditionally went kaput after about 100. But it looks like they are getting pretty close to something feasible, from the article: "The best performing copolymer consisted of 90% sulfur by mass. Batteries using this copolymer had an initial storage capacity of 1,225 mAh per gram of material. After 100 charge-discharge cycles, the capacity dropped to 1,005 mAh/g, and after 500 cycles it fell to about 635 mAh/g. In comparison, a lithium-ion battery typically starts out with a storage capacity of 200 mAh/g but maintains it for the life of the battery, Pyun says."

I saw an interesting graph in Aviation Week some time ago about the energy density of batteries versus the same mass of hydrocarbon fuel. The article was in relation to the idea of creating (plug-in) hybrid airliners.

The batteries used in the 787 store four orders of magnitude less energy than the equivalent mass of jet fuel.

I'm mentioning this because it looks like these batteries would bring the difference up to three orders of magnitude.

Still a ways to go before batteries can compete against hydrocarbon/fossil fuels.

There have been a lot of materials developments in battery designs over the last year or two. Some of them are providing 10x or better power storage with varying lifetimes. I'm really looking forward to seeing some of this make it into production. It would be better if they could couple improved batteries with some minimalist portable computer designs. People comfortable with Unix would get by with something with much lower specks than is typical today (assuming a minimalist interface), and the battery could probably last for hundreds of hours. I wouldn't mind that a bit.

Some of the other battery tech could be very useful for emergency situations.

With an iron anode, the energy content is roughly the same as petrol - ~ 10000 watt-hours per liter. But the most you can hope for an a straight gasoline ICE is about 30%, whereas a battery is likely to be 2.5x as efficient. A carbon anode, which is more likely to be developed is nearly double that of iron so if this tech pans out and it looks to be quite affordable, it'll kill the demand for fossil fuels in almost all light-duty vehicles and make it possible to have hybrid long-haul trucks.

Airliner turbines are extremely efficient at transforming energy into air movement. Because of expanding gasses in the burn process inside the turbine, roughly 9 times the amount of air being used in the burn process is being "propelled" on the outside of the engine. The mix of these at the back of the engine is also very carefully engineered. This results in an extremely efficient transformation, compared to a combustion engine as used in cars.
Getting the same amount of efficiency from an electrically driven turbine will be a challenge. Getting the same or better amount of efficiency from the system, including the primary generation of electricity, transporting it, battery losses and converting it in the electrical turbine doesn't sound very feasible at all. It's systems that matter, not components, right?

Lets see what the range on a typical light aircraft would be if you ripped out the full fuel tanks and gasoline engine and stuffed it with a equivalent power electric engine and these new batteries to the same weight. So it says it will store 4-5 times as much energy as todays best lithium-ion batteries. the best li-ion today is lithium cobalt, at about 165 wh/kg. So x4 of that is 660 wh/kg.

now, lets take a light plane for which I can find enough info to do this with, the jabiru j160D [jabiru.net.au] ok. so the fuel in it weighs (135L * 0.72kg/L) = 97.2kg. Now, the engine in it, the Jabiru 2200cc Aircraft Engine, weighs 62.8kg, and has a max power output of 60kw, and cruises at 75% power, so lets assume 50kw cruise power to account for takeoff and landing. So in total, engine and fuel weight 97.2 + 62.8 = 160kg

so lets rip that 160kg out and replace it with a EMRAX228 Brushless AC electric Motor with a 100kw power output and weighing in at 11.9kg, leaving us 148.1 kg worth of batteries, with a energy storage capacity of 148.1 * 0.66 = 97.746 kwh. so, at the cruise speed of 100knots = 185.2km/h, your looking at a range of (97.746kwh / 50kw) * 185.2km/h = 362km in about 2 hours.

The gasoline version can fly at the same speed for 8.5 hours. So, sure, the range is a quarter of the gasoline one, but you could ditch a passenger, chuck another 100kg of batteries in there and get that up to about 3.5 hours and 630km of range. Pretty damn good for a few dollars of electricity, negligible maintainence costs on a electric engine vs gasoline engine. sure as hell beats the $100+ youll pay for fuel alone for that same 3.5 hour trip.